The invention relates to a tank-cleaning device, having a housing insertable into an opening of a tank, which housing has a rotationally fixed housing part communicating with an ink for the cleaning fluid and a nozzle holder rotatable relative to the rotationally fixed housing part about a first pivot axis, and having at least one nozzle assembly with four nozzles that is disposed on the nozzle holder rotatably about a second pivot axis.
A similar tank-cleaning device is known from European Patent Disclosure EP 0 430 659 A2. This known tank-cleaning device has a slender housing, which can be introduced even into a narrow tank opening. The nozzle assembly has only two nozzles, which are disposed at an angle of 180xc2x0 to one another. When the housing is introduced into a narrow tank opening, the nozzle assembly is rotated in such a way that the common axis of the two nozzles is parallel to the longitudinal axis of the housing. The tank opening therefore has to have an only slightly greater diameter than the slender housing of the tank-cleaning device. A small tank opening can advantageously be manufactured much more economically than a large one.
On the inside surface of the tank, during the cleaning operation, the two nozzles create a certain netlike spray pattern, which at a fixed, predetermined ratio of the two rotary motions about the two aforementioned pivot axes is always repeated after a certain number of rotations and has a fixed xe2x80x9cmesh widthxe2x80x9d. The paths traced on the inside surface of the tank by the fluid streams come to have a fixed density, which cannot be increased even by providing a long cleaning period, since the fluid streams always travel along the same paths.
In other known devices, the cleaning density has therefore been reduced by the disposition of four nozzles instead of two nozzles. The four nozzles in the known nozzle assemblies are always disposed at uniform angular intervals of 90xc2x0 each from one another. The reason for this is that in the known tank-cleaning devices, the nozzles rotate uniformly about a typically horizontally disposed pivot axis, while the entire nozzle assembly rotates uniformly about a typically vertical pivot axis. Given the equal 90xc2x0 angular spacings of the nozzles, the result is accordingly a uniform spray pattern without major gaps on the inside surface of the tank.
The known nozzle assemblies with four nozzles have the disadvantage, however, that when they are introduced into a narrow tank opening, not all the nozzle axes can be adjusted parallel to the longitudinal axis of the housing anymore, or at least not unless further complicated engineering provisions are made. With very narrow tank openings, one is therefore forced to shorten the nozzle length, but this leads to a poorer quality of the fluid stream and less-effective cleaning, with poorer outcomes of cleaning. This means in turn, however, that so far, there has been no tank-cleaning device with four nozzles that fits through a narrow tank opening and nevertheless furnishes a fluid stream that attains effective cleaning.
The object of the present invention is therefore to disclose a tank-cleaning device which with a simple structure permits thorough cleaning of tanks with narrow tank openings.
This object is attained according to the invention in that two nozzles at a time of the nozzle assembly are disposed at an acute angle to one another in the form of respective V-formations, and the two V-formations have essentially opposed directions.
Surprisingly, it has been found that with the arrangement of nozzles in V-formations that form an acute angle, in accordance with the invention, a uniform spray pattern without major gaps can be created. If this nozzle assembly is rotated such that one V-formation points upward and the other points downward, then the longer dimension of the nozzle assembly is oriented in the direction of the longitudinal axis of the housing. The minimum required diameter of the tank opening is then determined only by the housing width and by the slenderer dimension of the nozzle assembly.
In a preferred embodiment, it is provided that the rotation of the nozzle holder about the first pivot axis and the rotation of the nozzle assembly about the second pivot axis are mechanically coupled to one another and have a fixed ratio to one another, so that the spray pattern repeats after a certain number of revolutions, and that the acute angles of the V-formations are adapted to the ratio of the two rotations with a view to a uniform spray pattern. If the ratio of the rotations is fixed, then by a skilled selection of the acute angle a uniform spray pattern without major gaps can be created that does not substantially differ from the spray pattern of known tank-cleaning devices that have four nozzles each disposed at right angles.
If the first pivot axis coincides with the longitudinal axis of the housing and is disposed perpendicular to the second pivot axis, and if the ratio of the two rotations is 45:43, then with a view to a uniform spray pattern it is optimal that the acute angles of the V-formations amount to approximately 40xc2x0. With this arrangement of the pivot axes, uniform rotary motions can be generated by simple means. It can be calculated that at the aforementioned ratio of the two rotations, the following angles between the nozzles can be considered for attaining a uniform spray pattern: 90.00xc2x0; 81.63xc2x0; 73.26xc2x0; 64.88xc2x0; 56.51xc2x0; 48.14xc2x0; 39.77xc2x0; 31.40xc2x0; 23.02xc2x0; 14.65xc2x0; and 6.28xc2x0. The angle of 39.77xc2x0 chosen here, or in round numbers 40xc2x0, represents an advantageous compromise with a view to a uniformly dense spray pattern with the smallest possible tank opening.
The provision that the two V-formations are disposed symmetrically to one another, so that two nozzles at a time point in opposite directions also contributes to the uniformity of the spray pattern.
If the two V-formations are disposed offset from one another, so that their pointed tips are each radially spaced apart from the second pivot axis, and the connecting line between the two pointed tips is substantially perpendicular to the angle bisector of the two acute angles, then the nozzles can be embodied advantageously long while optimally utilizing the little installation space available, so as to improve the quality of the fluid stream and the effectiveness of the cleaning.
If a turbine and a gear for driving the rotatable nozzle assembly are disposed in the elongated and slender rotationally fixed housing part in such a way that the cleaning fluid flowing in under pressure from the ink flows through the housing and drives the turbine before it emerges from the nozzles, then a slender device is obtained which is suitable for introduction into narrow tank openings and includes a simple drive mechanism for the two rotary motions, so as to assure thorough, uniform cleaning of the inside surfaces of the tank.
The invention can be improved still further in that an angular play of approximately 180xc2x0 is provided between an element that drives the rotary motion of the nozzle assembly about the second pivot axis and the drive shaft of the nozzle assembly. As a result, in the range of the angular play, an alignment of the nozzle assembly longitudinally of the housing is made possible from any arbitrary rotary position, without having to activate the rotational drive mechanism. It is therefore possible for a nozzle assembly that may not be positioned correctly to be aligned by hand for insertion into a narrow tank opening, without having to rotate the drive elements as well, and without unnecessarily using up the cleaning fluid otherwise required for drive purposes.
In an advantageous feature of the aforementioned angular play, the drive shaft is provided with a pin, which protrudes radially past its outside diameter and engages a recess, extending in the direction of rotation over an angular range of 180xc2x0, in the hub region of a cone wheel supported rotatably on the drive shaft.
Another advantageous feature provides that a platelike baffle connected to the drive shaft in a manner fixed against relative rotation, in the hub region, has a first protrusion protruding axially inward and extending in the direction of rotation over an angular range of 90xc2x0; that a cone wheel rotatably supported on the drive shaft, in the hub region, has a second protrusion protruding axially outward, counter to the first protrusion, projecting in the same axial region as the first protrusion and extending in the direction of rotation over an angular range of 90xc2x0, so that the relative rotation between the platelike baffle and the cone wheel is limited to an angular range of 180xc2x0 by the protrusions stopping against one another in the direction of rotation. The protrusions can be integrally molded in a simple way during production, in particular simultaneously with the casting of the cone wheel and baffle, with requiring further work steps such as inserting a pin into the drive shaft.